pre "tin" the conector and wire (heat them and melt some solder on them)=heat the connector for a few seconds (3-5) touch the solder to the iron so a couple drops melt then let the melted solder touch the connector. The melted solder will conduct alot more heat so the connector gets tinned without melting any plastic insulation. As soon as this solder starts to run (spreads on the metal which is now hot ) touch the wire to the conector and its solder should melt quickly and every thing runs together. Remove heat while not moving the wire. and in a couple seconds its cold

Another tip (no pun intended) is to match the size of soldering iron tip to the work to be done. Small tip for small solder joint - big tip for big solder joint etc. If you use to small a tip you will most likely wind up with a cold solder joint - if you use to big a tip then you "could" wind up burning the circuit board or component if you applied the iron for to long.

ps - wear some safety glasses!

__________________
DIY audio can be expensive – but getting to see things go up in smoke - that's priceless!!!! ..... "whatever - call it brainfart of Mighty ZM"

If this Crate is a couple of years old or more make sure you use tin/lead solder not lead free. Using lead free solder on an item made with lead solder is asking for trouble with poor / dry joints IMHO.

As its a 1/4" jack being soldered a temp controlled iron is helpful. small (15watt) irons probably will not have enough heat